Nature-based solutions for municipal wastewater treatment: A systematic review on full-scale systems from the last 30 years (1995–2025)

• A global review of full-scale NbS for municipal wastewater treatment is analyzed. • 393 full-scale NbS reviewed across 57 countries for wastewater treatment. • 7 NbS types were evaluated, with horizontal subsurface flow constructed wetland being the most prevalent (176 systems). • 31 substrates were identified, with gravel as the most common (n.205). • A total of 20 4 plant species were recorded in NbS worldwide, with the most used genera being Phragmites, Typha, Canna, Scirpus, and Salix. • The Aerated-CW showed the highest average contaminant removal efficiency. Nature-based Solutions (NbS) for municipal wastewater treatment have emerged as sustainable alternatives to increase global access to sanitation. This study has analyzed the global distribution and key design characteristics of NbS over the past 30 years, focusing on full-scale municipal wastewater treatment systems. This systematic review has identified 393 NbS from 249 publications from 57 countries. Seven NbS types are presented as different designs of constructed wetlands. The analysis reported the advantages and limitations, the main design parameters, the types of substrates and macrophytes used, and the removal efficiency of the main physical-chemical and microbiological parameters for each NbS. The most common NbS identified were horizontal subsurface flow constructed wetlands (HF-CW), while aerated constructed wetlands (Aerated-CW) were the least common. The Aerated-CW and vertical subsurface flow constructed wetlands (VF-CW) presented the highest hydraulic loading rates (210 and 120 mm d⁻¹, respectively) and the lowest specific surface area requirements (0.95 and 0.50 m 2 PE -1 , respectively). The research highlighted several types of substrates (n=31) and a high number of macrophyte species (n=204) used in NbS worldwide. The most common macrophyte genera used in NbS were Phragmites , followed by Typha, Canna, Salix, Cyperus, and Scirpus . Gravel, sand, soil, and stone are the most common substrates identified. The Aerated-CW showed the highest average efficiencies for organic matter (BOD 5 : 97.3 ± 1.37%; COD: 77.26 ± 31.69%) and nutrients (TN: 74.00 ± 22.64%, NH 4 : 90.90 ± 15.56%, and TP: 90.3 ± 9.33%). This research can contribute to the increasing knowledge of NbS, offering practical perspectives for local policy-makers and designers, and promoting their large-scale implementation.